libgcc/config/i386/gthr-win32.c - gcc - Git at Google

 /* Implementation of W32-specific threads compatibility routines for
    libgcc2.  */

 /* Copyright (C) 1999-2021 Free Software Foundation, Inc.
    Contributed by Mumit Khan <khan@xraylith.wisc.edu>.
    Modified and moved to separate file by Danny Smith
    <dannysmith@users.sourceforge.net>.

 This file is part of GCC.

 GCC is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free
 Software Foundation; either version 3, or (at your option) any later
 version.

 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or
 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 for more details.

 Under Section 7 of GPL version 3, you are granted additional
 permissions described in the GCC Runtime Library Exception, version
 3.1, as published by the Free Software Foundation.

 You should have received a copy of the GNU General Public License and
 a copy of the GCC Runtime Library Exception along with this program;
 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 <http://www.gnu.org/licenses/>.  */

 #include <windows.h>
 #ifndef __GTHREAD_HIDE_WIN32API
 # define __GTHREAD_HIDE_WIN32API 1
 #endif
 #undef  __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
 #define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
 #include "gthr-win32.h"

 /* Windows32 threads specific definitions. The windows32 threading model
    does not map well into pthread-inspired gcc's threading model, and so
    there are caveats one needs to be aware of.

    1. The destructor supplied to __gthread_key_create is ignored for
       generic x86-win32 ports. This will certainly cause memory leaks
       due to unreclaimed eh contexts (sizeof (eh_context) is at least
       24 bytes for x86 currently).

       This memory leak may be significant for long-running applications
       that make heavy use of C++ EH.

       However, Mingw runtime (version 0.3 or newer) provides a mechanism
       to emulate pthreads key dtors; the runtime provides a special DLL,
       linked in if -mthreads option is specified, that runs the dtors in
       the reverse order of registration when each thread exits. If
       -mthreads option is not given, a stub is linked in instead of the
       DLL, which results in memory leak. Other x86-win32 ports can use
       the same technique of course to avoid the leak.

    2. The error codes returned are non-POSIX like, and cast into ints.
       This may cause incorrect error return due to truncation values on
       hw where sizeof (DWORD) > sizeof (int).

    3. We are currently using a special mutex instead of the Critical
       Sections, since Win9x does not support TryEnterCriticalSection
       (while NT does).

    The basic framework should work well enough. In the long term, GCC
    needs to use Structured Exception Handling on Windows32.  */

 int
 __gthr_win32_once (__gthread_once_t *once, void (*func) (void))
 {
   if (once == NULL || func == NULL)
     return EINVAL;

   if (! once->done)
     {
       if (InterlockedIncrement (&(once->started)) == 0)
         {
 	  (*func) ();
 	  once->done = TRUE;
 	}
       else
 	{
 	  /* Another thread is currently executing the code, so wait for it
 	     to finish; yield the CPU in the meantime.  If performance
 	     does become an issue, the solution is to use an Event that
 	     we wait on here (and set above), but that implies a place to
 	     create the event before this routine is called.  */
 	  while (! once->done)
 	    Sleep (0);
 	}
     }
   return 0;
 }

 /* Windows32 thread local keys don't support destructors; this leads to
    leaks, especially in threaded applications making extensive use of
    C++ EH. Mingw uses a thread-support DLL to work-around this problem.  */

 int
 __gthr_win32_key_create (__gthread_key_t *key,
 			 void (*dtor) (void *) __attribute__((unused)))
 {
   int status = 0;
   DWORD tls_index = TlsAlloc ();
   if (tls_index != 0xFFFFFFFF)
     {
       *key = tls_index;
 #ifdef MINGW32_SUPPORTS_MT_EH
       /* Mingw runtime will run the dtors in reverse order for each thread
          when the thread exits.  */
       status = __mingwthr_key_dtor (*key, dtor);
 #endif
     }
   else
     status = (int) GetLastError ();
   return status;
 }

 int
 __gthr_win32_key_delete (__gthread_key_t key)
 {
   return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
 }

 void *
 __gthr_win32_getspecific (__gthread_key_t key)
 {
   DWORD lasterror;
   void *ptr;
   lasterror = GetLastError();
   ptr = TlsGetValue(key);
   SetLastError( lasterror );
   return ptr;
 }

 int
 __gthr_win32_setspecific (__gthread_key_t key, const void *ptr)
 {
   if (TlsSetValue (key, CONST_CAST2(void *, const void *, ptr)) != 0)
     return 0;
   else
     return GetLastError ();
 }

 void
 __gthr_win32_mutex_init_function (__gthread_mutex_t *mutex)
 {
   mutex->counter = -1;
   mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL);
 }

 void
 __gthr_win32_mutex_destroy (__gthread_mutex_t *mutex)
 {
   CloseHandle ((HANDLE) mutex->sema);
 }

 int
 __gthr_win32_mutex_lock (__gthread_mutex_t *mutex)
 {
   if (InterlockedIncrement (&mutex->counter) == 0 ||
       WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
     return 0;
   else
     {
       /* WaitForSingleObject returns WAIT_FAILED, and we can only do
          some best-effort cleanup here.  */
       InterlockedDecrement (&mutex->counter);
       return 1;
     }
 }

 int
 __gthr_win32_mutex_trylock (__gthread_mutex_t *mutex)
 {
   if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
     return 0;
   else
     return 1;
 }

 int
 __gthr_win32_mutex_unlock (__gthread_mutex_t *mutex)
 {
   if (InterlockedDecrement (&mutex->counter) >= 0)
     return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
   else
     return 0;
 }

 void
 __gthr_win32_recursive_mutex_init_function (__gthread_recursive_mutex_t *mutex)
 {
   mutex->counter = -1;
   mutex->depth = 0;
   mutex->owner = 0;
   mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL);
 }

 int
 __gthr_win32_recursive_mutex_lock (__gthread_recursive_mutex_t *mutex)
 {
   DWORD me = GetCurrentThreadId();
   if (InterlockedIncrement (&mutex->counter) == 0)
     {
       mutex->depth = 1;
       mutex->owner = me;
     }
   else if (mutex->owner == me)
     {
       InterlockedDecrement (&mutex->counter);
       ++(mutex->depth);
     }
   else if (WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
     {
       mutex->depth = 1;
       mutex->owner = me;
     }
   else
     {
       /* WaitForSingleObject returns WAIT_FAILED, and we can only do
          some best-effort cleanup here.  */
       InterlockedDecrement (&mutex->counter);
       return 1;
     }
   return 0;
 }

 int
 __gthr_win32_recursive_mutex_trylock (__gthread_recursive_mutex_t *mutex)
 {
   DWORD me = GetCurrentThreadId();
   if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
     {
       mutex->depth = 1;
       mutex->owner = me;
     }
   else if (mutex->owner == me)
     ++(mutex->depth);
   else
     return 1;

   return 0;
 }

 int
 __gthr_win32_recursive_mutex_unlock (__gthread_recursive_mutex_t *mutex)
 {
   --(mutex->depth);
   if (mutex->depth == 0)
     {
       mutex->owner = 0;

       if (InterlockedDecrement (&mutex->counter) >= 0)
 	return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
     }

   return 0;
 }

 int
 __gthr_win32_recursive_mutex_destroy (__gthread_recursive_mutex_t *mutex)
 {
   CloseHandle ((HANDLE) mutex->sema);
   return 0;
 }
	/* Implementation of W32-specific threads compatibility routines for
	libgcc2. */

	/* Copyright (C) 1999-2021 Free Software Foundation, Inc.
	Contributed by Mumit Khan <khan@xraylith.wisc.edu>.
	Modified and moved to separate file by Danny Smith
	<dannysmith@users.sourceforge.net>.

	This file is part of GCC.

	GCC is free software; you can redistribute it and/or modify it under
	the terms of the GNU General Public License as published by the Free
	Software Foundation; either version 3, or (at your option) any later
	version.

	GCC is distributed in the hope that it will be useful, but WITHOUT ANY
	WARRANTY; without even the implied warranty of MERCHANTABILITY or
	FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	for more details.

	Under Section 7 of GPL version 3, you are granted additional
	permissions described in the GCC Runtime Library Exception, version
	3.1, as published by the Free Software Foundation.

	You should have received a copy of the GNU General Public License and
	a copy of the GCC Runtime Library Exception along with this program;
	see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
	<http://www.gnu.org/licenses/>. */

	#include <windows.h>
	#ifndef __GTHREAD_HIDE_WIN32API
	# define __GTHREAD_HIDE_WIN32API 1
	#endif
	#undef __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
	#define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
	#include "gthr-win32.h"

	/* Windows32 threads specific definitions. The windows32 threading model
	does not map well into pthread-inspired gcc's threading model, and so
	there are caveats one needs to be aware of.

	1. The destructor supplied to __gthread_key_create is ignored for
	generic x86-win32 ports. This will certainly cause memory leaks
	due to unreclaimed eh contexts (sizeof (eh_context) is at least
	24 bytes for x86 currently).

	This memory leak may be significant for long-running applications
	that make heavy use of C++ EH.

	However, Mingw runtime (version 0.3 or newer) provides a mechanism
	to emulate pthreads key dtors; the runtime provides a special DLL,
	linked in if -mthreads option is specified, that runs the dtors in
	the reverse order of registration when each thread exits. If
	-mthreads option is not given, a stub is linked in instead of the
	DLL, which results in memory leak. Other x86-win32 ports can use
	the same technique of course to avoid the leak.

	2. The error codes returned are non-POSIX like, and cast into ints.
	This may cause incorrect error return due to truncation values on
	hw where sizeof (DWORD) > sizeof (int).

	3. We are currently using a special mutex instead of the Critical
	Sections, since Win9x does not support TryEnterCriticalSection
	(while NT does).

	The basic framework should work well enough. In the long term, GCC
	needs to use Structured Exception Handling on Windows32. */

	int
	__gthr_win32_once (__gthread_once_t once, void (func) (void))
	{
	if (once == NULL \|\| func == NULL)
	return EINVAL;

	if (! once->done)
	{
	if (InterlockedIncrement (&(once->started)) == 0)
	{
	(*func) ();
	once->done = TRUE;
	}
	else
	{
	/* Another thread is currently executing the code, so wait for it
	to finish; yield the CPU in the meantime. If performance
	does become an issue, the solution is to use an Event that
	we wait on here (and set above), but that implies a place to
	create the event before this routine is called. */
	while (! once->done)
	Sleep (0);
	}
	}
	return 0;
	}

	/* Windows32 thread local keys don't support destructors; this leads to
	leaks, especially in threaded applications making extensive use of
	C++ EH. Mingw uses a thread-support DLL to work-around this problem. */

	int
	__gthr_win32_key_create (__gthread_key_t *key,
	void (dtor) (void ) __attribute__((unused)))
	{
	int status = 0;
	DWORD tls_index = TlsAlloc ();
	if (tls_index != 0xFFFFFFFF)
	{
	*key = tls_index;
	#ifdef MINGW32_SUPPORTS_MT_EH
	/* Mingw runtime will run the dtors in reverse order for each thread
	when the thread exits. */
	status = __mingwthr_key_dtor (*key, dtor);
	#endif
	}
	else
	status = (int) GetLastError ();
	return status;
	}

	int
	__gthr_win32_key_delete (__gthread_key_t key)
	{
	return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
	}

	void *
	__gthr_win32_getspecific (__gthread_key_t key)
	{
	DWORD lasterror;
	void *ptr;
	lasterror = GetLastError();
	ptr = TlsGetValue(key);
	SetLastError( lasterror );
	return ptr;
	}

	int
	__gthr_win32_setspecific (__gthread_key_t key, const void *ptr)
	{
	if (TlsSetValue (key, CONST_CAST2(void , const void , ptr)) != 0)
	return 0;
	else
	return GetLastError ();
	}

	void
	__gthr_win32_mutex_init_function (__gthread_mutex_t *mutex)
	{
	mutex->counter = -1;
	mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL);
	}

	void
	__gthr_win32_mutex_destroy (__gthread_mutex_t *mutex)
	{
	CloseHandle ((HANDLE) mutex->sema);
	}

	int
	__gthr_win32_mutex_lock (__gthread_mutex_t *mutex)
	{
	if (InterlockedIncrement (&mutex->counter) == 0 \|\|
	WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
	return 0;
	else
	{
	/* WaitForSingleObject returns WAIT_FAILED, and we can only do
	some best-effort cleanup here. */
	InterlockedDecrement (&mutex->counter);
	return 1;
	}
	}

	int
	__gthr_win32_mutex_trylock (__gthread_mutex_t *mutex)
	{
	if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
	return 0;
	else
	return 1;
	}

	int
	__gthr_win32_mutex_unlock (__gthread_mutex_t *mutex)
	{
	if (InterlockedDecrement (&mutex->counter) >= 0)
	return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
	else
	return 0;
	}

	void
	__gthr_win32_recursive_mutex_init_function (__gthread_recursive_mutex_t *mutex)
	{
	mutex->counter = -1;
	mutex->depth = 0;
	mutex->owner = 0;
	mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL);
	}

	int
	__gthr_win32_recursive_mutex_lock (__gthread_recursive_mutex_t *mutex)
	{
	DWORD me = GetCurrentThreadId();
	if (InterlockedIncrement (&mutex->counter) == 0)
	{
	mutex->depth = 1;
	mutex->owner = me;
	}
	else if (mutex->owner == me)
	{
	InterlockedDecrement (&mutex->counter);
	++(mutex->depth);
	}
	else if (WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
	{
	mutex->depth = 1;
	mutex->owner = me;
	}
	else
	{
	/* WaitForSingleObject returns WAIT_FAILED, and we can only do
	some best-effort cleanup here. */
	InterlockedDecrement (&mutex->counter);
	return 1;
	}
	return 0;
	}

	int
	__gthr_win32_recursive_mutex_trylock (__gthread_recursive_mutex_t *mutex)
	{
	DWORD me = GetCurrentThreadId();
	if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
	{
	mutex->depth = 1;
	mutex->owner = me;
	}
	else if (mutex->owner == me)
	++(mutex->depth);
	else
	return 1;

	return 0;
	}

	int
	__gthr_win32_recursive_mutex_unlock (__gthread_recursive_mutex_t *mutex)
	{
	--(mutex->depth);
	if (mutex->depth == 0)
	{
	mutex->owner = 0;

	if (InterlockedDecrement (&mutex->counter) >= 0)
	return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
	}

	return 0;
	}

	int
	__gthr_win32_recursive_mutex_destroy (__gthread_recursive_mutex_t *mutex)
	{
	CloseHandle ((HANDLE) mutex->sema);
	return 0;
	}